Tretinoin: a dermatological solution

Retinol (vitamin A1)

Retinol (vitamin A1) is a vitamin compound within the vitamin A family, created by the body using the beta carotene in our diet. Beta carotene is contained in red and orange vegetables and fruits, such as tomatoes, carrots and oranges, etc., and in animal meats, especially in liver.

After intestinal absorption, the beta carotene is transported to the liver where it is converted into retinol molecules. These individual retinol molecules are then stored in specialized cells within the liver. These cells, known as HSCs, also contain lipids and vitamin A.

The role of vitamin A

Vitamin A is an important nutrient for vision, tissue growth and differentiation, cell division, reproduction, and immunity.

Vitamin A deficiency can cause problems including skin and eye dryness, intestinal disorders and infertility.

How vitamin A works

Vitamin A acts within cells by stimulating both cell reproduction and protein synthesis. To do this, it needs an entry key to unlock the cell membrane, without which it is unable to penetrate cells. This key comes in the form of a specific protein synthesized by the liver called retinol binding protein (RBP). The RBP complex is recognised by the receptor on the cell membrane, which then allows vitamin A to enter the cell and perform its role as a nutrient.

Why retinol applied to the skin doesn’t work

There are a huge number of retinol-based cosmetic products on the market, from creams, to lotions, to oils and balms. There is also a popular belief that these products help the skin to regenerate and perform better, however, this is simply untrue and these products do not work. This is because retinol, as it appears in cosmetic products, cannot penetrate the skin cells as there is no RBP present, a protein of which occurs exclusively in the liver.

From retinoids to retinoic acid (tretinoin)

Within the body, retinol is first transformed into retinaldehyde, and finally into retinoic acid. Even though there is less of it produced compared to retinol, retinoic acid has an important function in cell maturation and differentiation of the even deeper epidermal cells. Unlike retinol, it does not need any binding protein to penetrate the inside of a cell because a specific receptor for retinoic acid already exists on the cell membrane.

Retinoic acid and the skin

When applied to the skin, retinoic acid immediately begins stimulating cell regeneration by accelerating turn over and differentiating damaged or deviated cells. Therefore, retinoic acid can be used in many pathological situations within dermatology:

• Acne > prevents hyperkeratosis of follicles
• Photoaging > differentiates sun-damaged cells into normal cells
• Melasma > increases cell turnover by rapidly eliminating excess melanin

How to avoid retinoic acid toxicity

When too much retinoic acid is administered to the skin, it can cause toxicity that results in redness, dryness and itching. This is referred to as retinoic dermatitis. Studies have found that one administration of tretinoin changes cell behavior for up to four days. This means that, if the tretinoin is applied daily or even several times per day, the cells will go into toxicity. The correct dose of tretinoin that will still deliver results is one or two non-consecutive applications per week.

Why tretinoin should be used as a solution, and not as a cream

In the three main conditions for which tretinoin is used, cream is often not the right mode of application: in cases of acne, the cream penetrates the follicles which inhibits the release of comedones; in cases of photodamaged skin and melasma, cream slows down desquamation and cell renewal. Instead, tretinoin solution gives a far better result and is easier to dose, as the user can precisely calculate the number of drops to be applied to the skin.

Prescription for tretinoin solution

Tretinoin 0.05 %

Propylene Glycol 40 %

Ethyl Alcohol (96%) 59.9 %

AlphaTocopherol 0.05%

Stored in a dark 50 ml bottle with a dropper cap.